The present invention relates to pain management. In particular, the invention relates to intramuscular stimulation therapy utilizing pin (i.e. needle) penetration and manipulation to help relieve severe chronic pain for which a specific cause cannot be determined, and for which medicinal and other usual methods of pain relief have proven ineffective, i.e., neuropathic pain.
Non-chemical, non-electrical intramuscular stimulation (IMS) is used in the management of regional and diffuse myofascial pain (fibromylagia) of radiculopathic origin where musculoskeletal pain resulting from muscle shortening is the predominant feature. Unlike acupuncture, where many pins which remain stationary are inserted into points on imaginary meridians, in IMS generally only one pin is used at a time. The pin, which is inserted into a tender muscle motor point, is continuously manipulated to achieve pain relief. The IMS technique was pioneered by C. Chan Gunn, M.D. and is described in the following publications, each of which is, in its entirety, incorporated by reference herein: Gunn C. C. et al., Dry Needling of Muscle Motor Points for Chronic Low-Back Pain, A Randomized Clinical Trial With Long-Term Follow-Up, Spine, Vol. 5 No. 3, May/June 1980, pp. 279-291; Gunn C. C., Treatment of Chronic Pain. Intramuscular Stimulation for Myofascial Pain of Radiculopathic Origin. London, UK, Churchill Livingston, 1996.
Building on the work of Gunn, and based upon a clinical study of pain relief experienced by patients who have undergone electromyography (EMG) to determine the effects of IMS on pain symptoms, the present physician inventor developed and has used with success a modified IMS technique. In EMG, a pin electrode is inserted into muscles for detection of electromyographic signals. During EMG, the pin is moved in all directions for examination of the electrical activity of the muscle during rest, and minimal and maximal contraction. The inventor's modified IMS technique focuses on eliciting twitch responses from muscles by stimulation of motor end plate zones, as opposed to stimulation of motor points as described by Gunn. In the inventor's original technique, a somewhat randomly directed needle insertion was followed with needle movement in all directions and at different depths in the muscle, as in EMG studies, in order to localize and accurately position the pin in the motor end-plate zone. See Chu J., Dry Needling (Intramuscular Stimulation) In Myofacsial Pain Related To Lumbosacral Radiculopathy, Eur. J. Phys. Med And Rehabil. 5(4): 106-121, 1995 (hereby incorporated by reference in its entirety). Later, the present inventor observed that increased pain relief effects could be obtained by needling muscle tender points with a simple in-out motion of a needle along the myofascial bands of the muscles.
IMS, whether in accordance with the modality taught by Gunn or that taught by the present inventor, has been performed manually. In accordance with Gunn's teaching, a thin flexible acupuncture needle is inserted into the patient's flesh utilizing a tubular guide. The needle is attached at its proximal end to a distal end of a plunger which is reciprocable within the guide. The plunger protrudes from the proximal end of the tubular guide to provide a finger grip surface, whereby the plunger (and attached needle) can be advanced and retracted. An example of such a tubular guide is the Showa #6 available from Nikka Industries Ltd., Vancouver, B.C., Canada. In accordance with the inventor's modified IMS technique, the same type of tubular guide can be used. However, a stiffer EMG needle is preferred for certain applications.
Despite its effectiveness in ultimately providing pain relief, the manual IMS treatment is itself quite painful to the patient. The pain is primarily due to the irregular deflection of the needle from its proper path as it is manually pushed in and pulled out repetitively through tissues of differing resiliencies. With the manual method of IMS, it is difficult to maintain proper positioning and directivity of the needle insertion with each to and fro movement, because of the manual effort required of the physician. As a result, the twitch point is easily lost. In such a situation, the pin direction is changed (often several times) within the muscle in order to return the pin to the vicinity of the twitch point. This causes significant additional discomfort to the patient, as well as increased bleeding and tissue trauma. Uneven starts and stops within the muscle are also inevitable because the movements are dependent on the treating physician's skill and strength on encountering different resistance of skin, subcutaneous and muscle tissue at any given point. Less pain would be experienced by the patient if the pin movements could be kept regular, even and steady.
In addition, the work involved on the physician's part in performing manual IMS is laborious, tedious, time-consuming and likely to lead to repetitive stress injury. This is due to the repetitive and resisted upper extremity movements required in performing the procedure. The problem for physicians is particularly acute when, as is typically the case, many areas of a patient's body have to be treated in one session, and when the majority of the patients require this type of multi-area treatment. Under these circumstances, physicians performing manual IMS on a long term basis likely will suffer from repetitive strain injuries and eventually have to stop practicing the method.